Detroit has at least one thing Silicon Valley doesn’t: snow. And Ford is taking advantage of that to test how its autonomous vehicles perform when they can’t see lane markings.

The laser-imaging LIDAR sensors on the top of this Ford test car rely on the markings to keep the car in its place on the road, so snow and slush presents a problem.

The automaker is getting around this problem by using what the sensors can see: buildings, light poles and traffic signals, to match the car’s position against a highly accurate map that’s been preloaded in the car’s computer. The lanes are also mapped out in that data, so the car can position itself where it knows the center of the lane to be.

“Snow is one of the most extreme driving conditions, which is also true for an autonomous vehicle. Snow blocks sensors, and obviously creates slippery conditions, so this testing will help us take fully autonomous vehicles to the ultimate level.”

Perhaps not ultimate level. There are many more challenges autonomous cars have to overcome to replace human drivers, which would be the ultimate level, but this is a step towards that.

The testing is taking place at Mcity, a fake city built by the University of Michigan that serves as a real-world substitute for autonomous driving testing. It gives automakers the chance to experiment and take greater risks than they can on public streets.

Ford is ploughing more resources into its autonomous driving program. Last week at CES, the company said it plans to triple its test fleet to about 30 cars — the biggest of any automaker, but still less than Google.

However, while the Internet company took an early lead, car companies are getting more serious about autonomous driving. It’s becoming a hot area of research.